Camry 2.2L 4-Cyl. CNG & Gasoline Models, Camry Solara 2.2L 4-Cyl. & RAV4
EGR system reduces oxides of nitrogen (NOx) emissions by lowering combustion temperatures. Combustion temperatures are lowered by recycling metered amount of exhaust gases back into intake system. EGR system contains a vacuum-operated EGR valve, EGR vacuum modulator and EGR Vacuum Switching Valve (VSV). See Fig 1. Amount of EGR operation is regulated by EGR vacuum modulator according to engine load. EGR valve operation is controlled by EGR VSV which is controlled by Engine Control Module (ECM). If ECM turns on EGR VSV, this causes EGR valve to close and shuts off the exhaust gas. ECM may shut off EGR system if any of the following conditions exist.
- Engine Is Not At Normal Operating Temperature
- During Deceleration With Throttle Closed
- During Light Or Heavy Engine Load
- Engine Is Idling
- Engine Speed Is Greater Than 4400 RPM
The ECM uses various input signals for controlling EGR system operation. For EGR system and component testing, see SYSTEM & COMPONENT TESTING - 4-CYLINDER article.